Androgen (male hormone) is mainly synthesized in the testes of adult males, and possesses the actions for maintaining the functions of the reproductive organ and accessory reproductive organs (prostate, seminal gland), spermatogenesis and the like. If the balance of androgen and estrogen (female hormone) is broken and the action of androgen is encouraged, it is known to induce benign prostatic hypertrophy, prostatic carcinoma, female hairiness, male baldness or pimple. Hypertrophy of the prostate is observed in about 30% of male of 60 years or elder, and symptoms of benign prostatic hypertrophy (BPH) such as dysuria are noted in half of them.
As androgen, testosterone, androstenedione, dehydroepiandrosterone, and others are known. It is also known that 85% of androgens synthesized in the tests of the adult men is testosterone.
The testosterone is transformed, in the cells of the prostate, into 5 .alpha.-dihydrotestosterone (5 .alpha.-DHT) by 5.alpha.-reductase, and is bound with a receptor to get into the nucleus, and activates the genes, thereby expressing the actions as mentioned above.
As substances inhibiting expression of such actions of androgens, for example, chlormadinone acetate, flutamide, and hydroxyflutamide are known. However, the androgen activity inhibiting actions by these compounds were not sufficiently satisfactory, the therapeutic effects on benign prostatic hypertrophy, prostatic carcinoma, female hairiness, male baldness or pimple were not sufficient.